Electrode Sheet Fabrication Device

This application claims the benefit of priority to Japanese Patent No. 2024-086699 filed on May 28, 2024. The entire contents of this application are hereby incorporated herein by reference.

The present disclosure relates to an electrode sheet fabrication device.

Japanese Patent Application Publication No. 2023-36089, for example, discloses a method for fabricating an electrode. In this method, in a precursor sheet (i.e., an electrode sheet) including metal foil, a coated portion coated with an electrode material on the metal foil, and an uncoated portion not coated with the electrode material on the metal foil, the uncoated portion is pressed by a pair of elastic rolls (i.e., rubber rolls).

For example, when the uncoated portion is pressed with rolls other than elastic rolls, voids can occur by a tensile force or other reasons inside the uncoated portion. These voids might cause breakage of the uncoated portion. By pressing the uncoated portion with the pair of elastic rolls, a compressive force and a deformation force can be applied to the same portion of the uncoated portion. This compressive force occurs by deformation of the elastic rolls caused by contact with the pair of elastic rolls. Accordingly, the uncoated portion can be extended with suppression of breakage of the uncoated portion.

In the method for fabricating an electrode disclosed in Japanese Patent Application Publication No. 2023-36089, when the elastic rolls are kept pressed against the precursor sheet, pressed portions of the elastic rolls can be locally deformed. When the locally deformed elastic rolls rotate and are pressed against an uncoated portion, the degree of extension of the uncoated portion might vary.

An electrode sheet fabrication device disclosed here is a fabrication device that fabricates an electrode sheet including a current collector of long metal foil, a non-formed portion defined along a length direction at a predetermined position in a width direction in the current collector, and an electrode active material layer located on a portion of the current collector except for the non-formed portion and including an electrode active material. The fabrication device includes: a conveyor that conveys the electrode sheet along a predetermined conveyance path; a support roll that is located on the conveyance path and supports, along the width direction, a first surface of the electrode sheet conveyed along the conveyance path; a pressing roll located at a second surface of the electrode sheet and facing the support roll; a driver that presses the pressing roll against the support roll with the electrode sheet sandwiched between the pressing roll and the support roll; and a controller. The pressing roll is a rubber roll at least whose outer circumference surface is made of rubber and is located such that the non-formed portion is sandwiched between the pressing roll and the support roll except for the electrode active material layer of the electrode sheet. The driver includes a moving mechanism and a pressing mechanism. The moving mechanism moves the pressing roll to a first position at which the pressing roll is separated from the electrode sheet and a second position at which the pressing roll contacts the electrode sheet. The pressing mechanism that presses the pressing roll against the electrode sheet from the second position. The controller includes a movement controller, a conveyance controller, and a pressing controller. The movement controller that moves the pressing roll from the first position toward the second position before the conveyor starts conveyance of the electrode sheet. The conveyance controller that conveys the electrode sheet along the support roll after the pressing roll has moved to the second position by the movement controller. The pressing controller that presses the pressing roll against the electrode sheet from the second position when the conveyance controller starts conveyance of the electrode sheet or when a predetermined reference time has elapsed since the conveyance controller started conveyance of the electrode sheet.

In the electrode sheet fabrication device disclosed here, after the pressing roll has been located at the second position, conveyance of the electrode sheet is started. Then, when conveyance of the electrode sheet is started or when a reference time has elapsed since conveyance of the electrode sheet was started, the pressing roll is pressed against the electrode sheet from the second position. Accordingly, the timing of pressing the pressing roll against the electrode sheet from the second position is delayed, and thus, the pressing roll is less likely to be locally deformed. As a result, the uncoated portion of the electrode sheet can be pressed by using the pressing roll that is less likely to be locally deformed and the support roll, and thus, the uncoated portion can be easily extended uniformly.

A preferred embodiment of the technique disclosed here will be described hereinafter with reference to the drawings. The preferred embodiment described herein is, of course, not intended to particularly limit the present disclosure. Each drawing is a schematic view and does not necessarily strictly reflect an actual product. Members and parts having the same functions are denoted by the same reference numerals as appropriate, and description for the same members and parts will not be repeated as appropriate.

is a flowchart of fabrication by an electrode sheet fabrication device. As illustrated in, fabrication in the electrode sheet fabrication deviceincludes conveyance step S, measuring step S, kneading step S, coating step S, drying step S, and roll press step S. The fabrication in the electrode sheet fabrication devicemay include other steps.

In the electrode sheet fabrication device, an electrode sheet(see) constituting a power storage device is fabricated. The electrode sheetincludes a positive electrode sheet or a negative electrode sheet of an electrode body housed inside the power storage device. The power storage device refers to a device enabling repetitive charging and discharging, and generally includes so-called storage batteries (i.e., chemical cells) such as a lithium ion secondary battery, a nickel hydrogen battery, and a nickel-cadmium battery and capacitors (i.e., physical cells) such as an electric double layer capacitor. Hereinafter, as an example, the electrode sheet fabrication devicethat fabricates an electrode sheetwill be described together with a configuration of the electrode sheetfor use in lithium ion secondary batteries.

is a schematic view of the electrode sheet. As illustrated in, the electrode sheethas an elongated band shape. The electrode sheetincludes a current collectorand an electrode active material layer. The current collectoris a member of metal foil. The current collectoris an elongated band-shaped metal member. As the current collector, a metal material having required conductivity can be used. As positive electrode current collecting foil as an example of the current collector, aluminium or an aluminium alloy can be used, for example. As negative electrode current collecting foil as another example of the current collector, copper or a copper alloy can be used, for example. The electrode active material layeris applied onto a predetermined portion of the current collector. The electrode active material layeris formed on at least one surface of the band-shaped current collector. In this preferred embodiment, the electrode active material layeris formed on each surface of the current collector. The electrode active material layercontains an electrode active material. As a positive electrode active material that is an example of the electrode active material, a lithium transition metal composite oxide can be used, for example. As a negative electrode active material that is an example of the electrode active material, a carbon material, a silicon-based material, and a mixed oxide thereof can be used, for example. The electrode active material layer may include an additive other than the electrode active material layer, such as a binder or a conductive material.

The electrode sheetis formed by applying electrode mixture slurry as the electrode active material layeronto the current collectorand drying the slurry. The current collectorincludes uncoated portionsand a coated portion. The uncoated portionsare an example of a non-formed portion. The uncoated portionsare portions of the current collectornot coated with the electrode active material layer. The uncoated portionsare defined at predetermined positions of the current collectorin the width direction along the length direction. The uncoated portionsare defined along the length direction on end portions of the electrode sheetin the width direction. In this preferred embodiment, the uncoated portionsare defined at both ends of the electrode sheetin the width direction. The coated portionis located between the uncoated portionsat both ends of the electrode sheet. The coated portionis a portion of the current collectorcoated with the electrode active material layer. The electrode mixture slurry is applied onto the coated portion. In this manner, the electrode active material layeris formed on the coated portionof the current collector. That is, the electrode active material layeris located between the uncoated portionsat both ends of the electrode sheetin the width direction. The electrode active material layeris formed on a portion of the current collectorexcept for the uncoated portions. Although not shown, a protective layer including an inorganic filler may be located at the boundary between the uncoated portionsand the coated portion. In the case where the protective layer is formed, when rubber rolls of EPS are pressed against the protective layer, elongation percentages of a portion with the protective layer and a portion without the protective layer might not match.

In conveyance step Sshown in, the electrode sheetis conveyed.is a schematic side view of the electrode sheet fabrication device. In this preferred embodiment, the electrode sheet fabrication deviceincludes a conveyor. The conveyance step Scan be implemented by the conveyor. The conveyorconveys the electrode sheet. The conveyoremploys, for example, a motor. The conveyorincludes an unwinding rolland a winding rollsuch that the electrode sheetis conveyed at a predetermined conveyance speed. The electrode sheetis wound around the unwinding rolland the winding roll. The unwinding rollis disposed upstream of a roll pressing machinedescribed later in the conveyance direction. The winding rollis disposed downstream of the roll pressing machinein the conveyance direction. The conveyoris not limited to the configuration including the unwinding rolland the winding roll. For example, the conveyormay include a roll other than the unwinding rolland the winding roll. The conveyorconveys the electrode sheetalong a predetermined conveyance path.

In measuring step Sshown in, materials for the electrode active material layer(see) are measured. The measurement can be achieved using a measuring device (not shown) equipped with, for example, a balance or a load cell. The measured materials for the measured electrode active material layerare mixed in kneading step S. Kneading step Scan be achieved by a kneading device (not shown). A material for the electrode active material layermade into slurry by the kneading device is applied onto the current collector(see) by coating in coating step S. Coating step Scan be achieved by, for example, a coating device (not shown) such as a slit coater, a gravure coater, a die coater, or a comma coater. In drying step Sshown in, the applied slurry materials for the electrode active material layerare dried. Drying step Scan be achieved by a drying device (not shown) that emits, for example, hot air or an infrared ray.

In roll press step Sshown in, the electrode sheetis pressed. The electrode sheetis extended by pressing. The roll press step Scan be achieved by the roll pressing machineshown in. The electrode sheet fabrication deviceincludes the roll pressing machine. As illustrated in, the electrode sheetis pressed by the roll pressing machinein the middle of the conveyance path. The electrode sheetis supplied to the roll pressing machineby the unwinding roll. The electrode sheetpressed by the roll pressing machineis conveyed toward the winding rolland wound by the winding roll. The electrode sheet fabrication deviceincludes a controllerthat controls the unwinding roll, the winding roll, and the roll pressing machine.

is a front view of the roll pressing machine. The roll pressing machineaccording to this preferred embodiment presses the uncoated portionsof the electrode sheetby rubber rolls before or after the coated portionof the electrode sheetis pressed. When the uncoated portionsare pressed by the rubber rolls, under a reaction force of elastic deformation and compressive deformation of the rubber rolls, the portion pressed by the rubber rolls are pressed and pulled. Consequently, the uncoated portionscan be extended with breakage of the uncoated portionssuppressed. For this function, the device that presses the uncoated portionsof the electrode sheetby the rubber rolls can be referred to as an elasticity powered stretching (EPS) device. The electrode sheet fabrication devicemay include a device that presses the coated portion, other than the roll pressing machine.

As illustrated in, the roll pressing machineincludes a support roll, the pressing rolls, and a driver.

The support rollis located on the conveyance path(see). The support rollsupports a first surfaceD of the electrode sheetconveyed along the conveyance path, along the width direction of the electrode sheet. The electrode sheetincludes the first surfaceD and a second surfaceU. In this preferred embodiment, the first surfaceD constitutes a lower surface of the electrode sheet. The second surfaceU is a surface of the electrode sheetopposite to the first surfaceD. In this preferred embodiment, the second surfaceU constitutes an upper surface of the electrode sheet. The support rollis located below the pressing rolls. The support rollis a rubber roll that presses the uncoated portionsof the electrode sheettogether with the pressing rolls. In this preferred embodiment, the support rollincludes a bodyand both axial portions

is a cross-sectional view taken along line A-A in.illustrates a state where the uncoated portionsare pressed by the support rolland the pressing rolls. In, the pressing rollsare at a second position Pand press cylindersdescribed later (see) are on. As illustrated in, the bodyincludes an axis portionand a rubber portion. The axis portionis made of a metal. A material for the axis portionis not particularly limited, and is, for example, a material having a relatively high hardness such as SUS304 (stainless steel material). The rubber portioncovers at least the outer circumference surface of the axis portion. A material for the rubber portionis, for example, nitrile rubber (NBR). The support rollpresses the uncoated portionsof the electrode sheetwith the rubber portion

The support rollrotates in a predetermined direction by a rotation mechanismdescribed later (see). In this preferred embodiment, the support rollrotates in a direction of arrow Rshown in. At this time, the electrode sheetis conveyed from the left to the right when seen in the drawing of. That is, in, the left is an upstream side in the conveyance direction, and the right is a downstream side in the conveyance direction.

As illustrated in, the both axial portionsare inserted in the body. The both axial portionsare inserted in the axis portion(see) of the body. The both axial portionsextend to the outside of the support rollin the axial direction. Although not shown, a bearing and a gap screw that adjusts a gap between the support rolland the pressing rolls, for example, may be attached to the both axial portions

As illustrated in, the pressing rollspress the electrode sheetagainst the support roll. The pressing rollsare disposed to face the support rollon the second surfaceU (upper surface in this preferred embodiment) of the electrode sheet. The pressing rollssandwich the uncoated portionsbetween the pressing rollsand the support rollexcept for the coated portion(see) of the electrode sheet. In this preferred embodiment, the positions of the axial centers of the pressing rollsand the position of the axial center of the support rollare aligned in the top-bottom direction. As illustrated in, the pressing rollsare rubber rolls at least whose outer circumference surfaces are made of rubber. The pressing rollsare rubber rolls that press the uncoated portionsof the electrode sheettogether with the support roll. The pressing rollsare not located above the coated portionof the electrode sheet. In this preferred embodiment, as described above, two uncoated portionsof the electrode sheetare defined at both ends of the electrode sheetin the width direction. Thus, as illustrated in, the pressing rollsare respectively located above the uncoated portionsat both ends of the electrode sheetin the width direction. The number of the pressing rollsis two. The number of the uncoated portionsmay be one. In the case where the number of the uncoated portionsis one, the number of the pressing rollsmay be one. In the two pressing rolls, the left pressing rollwill also be referred to as a pressing rollL, and the right pressing rollwill also be referred to as a pressing rollR. In the case where the description applies to both pressing rollsL andR, the term “pressing roll” will be used as appropriate. In this preferred embodiment, the pressing rollincludes the bodyand the both axial portions

As illustrated in, the bodyincludes an axis portionand a rubber portion. The axis portionis made of a metal. A material for the axis portionis not particularly limited, and is, for example, a material having a relatively high hardness such as SUS304 (stainless steel material). The rubber portioncovers at least the outer circumference surface of the axis portion. A material for the rubber portionis not particularly limited and is, for example, nitrile rubber (NBR). The pressing rollpresses the uncoated portionof the electrode sheetwith the rubber portion

As illustrated in, the both axial portionsare inserted in the body. The both axial portionis inserted in the axis portion(see) of the body. The both axial portionsextend to the outside of the two pressing rollsin the axial direction. Although not shown, a bearing and a gap screw that adjusts a gap between the support rolland the pressing rolls, for example, are attached to the both axial portions

As illustrated in, when the support rollrotates in the direction of arrow Rwith the electrode sheetsandwiched between the support rolland the pressing rolls, the pressing rollsare subjected to a force of rotation in the direction of arrow Rthrough the electrode sheet. On the other hand, when the support rolland the pressing rollsare in contact with each other without the electrode sheet, the pressing rollsare subjected to a force of rotation in the direction of arrow Rby the rotation force of the support roll. Accordingly, the pressing rollsrotate in the direction of arrow R. That is, the pressing rollsare driven rolls that rotate in synchronization with rotation of the support roll.

The driverpresses the pressing rollsagainst the support rollwith the electrode sheetsandwiched between the pressing rollsand the support roll. In this example, as illustrated in, the driverincludes a moving mechanismand a pressing mechanism.

illustrates a state where the pressing rollsare located at a first position Pand corresponds to. The moving mechanismmoves the pressing rollsto the first position P(see) and the second position P(see). The first position Pand the second position Pherein are positions of the pressing rollswith respect to the support roll(e.g., the electrode sheetsupposed by the support roll). The first position Pis a position of the pressing rollswhen the pressing rollsare separated from the electrode sheetsupported by the support roll, as illustrated in. At the first position P, the pressing rollsare located above the support rolland separated from the support roll. The second position Pis a position of the pressing rollswhen the pressing rollscontact the electrode sheetsupported by the support roll, as illustrated in. At the second position P, the pressing rollscontact the second surfaceU of the electrode sheet. The second position Pis located below the first position P. At the second position P, the pressing rollsare mounted on the electrode sheetby self weight. While the electrode sheetis not supported by the support rolland the pressing rollsare at the second position P, the pressing rollsare in contact with the support roll. In this preferred embodiment, the moving mechanismmoves the pressing rollsbetween the first position Pand the second position P. The moving mechanismalso moves the pressing rollsupward and downward. The configuration of the moving mechanismis not particularly limited, and may be integrated with press cylindersdescribed later (see) or may be the press cylinders. For example, the moving mechanismmay be configured to move the pressing rollsalong rodsdescribed later of the press cylinders.

As illustrated in, the pressing mechanismpresses the pressing rollsagainst the electrode sheet. The pressing mechanismadjusts a force (i.e., pressing force) with which the pressing rollspress the electrode sheet. The pressing mechanismincludes the press cylinders, roll chocks, and a cylinder driving device.

The press cylinderpresses the pressing rollsagainst the support roll. One press cylinderis disposed on each outer side of one of both ends of the corresponding pressing roll. In this example, in, the press cylinderat the left of the electrode sheetwill also be referred to as a press cylinderL, and the press cylinderat the right of the electrode sheetwill also be referred to as a press cylinderR. In description common to the press cylindersL andR, the term “press cylinder” will also be used. In this preferred embodiment, the press cylindersare pneumatic cylinders. The press cylindersinclude rods. The rodsare connected to the roll chocks. The roll chocksrotatably support the both axial portionsof the pressing rolls. When the press cylindersare driven and the rodsmove downward, the pressing rollsmove downward. With the downward movement of the pressing rolls, the pressing rollsare pressed by the support roll, and the pressing force increases. When the press cylindersare driven and the rodsmove upward, the pressing rollsmove upward. The upward movement of the pressing rollsreduces the pressing force.

The cylinder driverpresses the pressing rollsagainst the support roll. The cylinder driveris connected to the press cylinders. The cylinder driverdrives the press cylinders. In this manner, the rodsof the press cylindersmove upward and downward. In this preferred embodiment, the cylinder driveris configured to drive the press cylinderL and the press cylinderR independently of each other. That is, the cylinder driverdrives the pressing rollslocated above the uncoated portionsat both ends of the electrode sheetin the width direction, independently of each other. The cylinder driveris connected to the controller(see).

In this preferred embodiment, the press cylindersis switchable between on and off by the cylinder driving device. While the press cylindersare off, the cylinder driving deviceis not driven, and the pressing rollsare not pressed against the electrode sheetby the press cylinders. While the press cylindersare on, the cylinder driving deviceis driven, and the pressing rollsare pressed against the electrode sheetby the cylinder driving deviceand the press cylinders.

illustrates a state where the pressing rollsare located at the second position Pand the press cylindersare off, and corresponds to. In this example, when the pressing rollsare at the second position P, the press cylindersare switched between on and off. As illustrated in, in a case where the press cylindersare off when the pressing rollsare at the second position P, for example, the pressing rollsare not pressed against the electrode sheetby the press cylindersand are mounted on the electrode sheetsupported by the support roll. At this time, the pressing rollscan be pressed against the electrode sheetto some degree by self weight. In this example, in the case where the pressing rollsare at the second position Pand the press cylindersare off, the pressing rollsare pressed against the electrode sheetwith a predetermined first load value V. The first load value Vis not limited to a particular value, and is, for example, 800 N or less.

As illustrated in, in a case where the pressing rollsare at the second position Pand the press cylindersare on, for example, the pressing rollsbecome the state of being pressed against the electrode sheetby the press cylindersby driving of the cylinder driving device. In this example, in the case where the pressing rollsare at the second position Pand the press cylindersare on, the pressing rollsare pressed against the electrode sheetwith a predetermined second load value V. The second load value Vis larger than the first load value V. The second load value Vis not limited to a particular value, and is, for example, 1000 N to 4000 N and may be 2000 N to 3000 N. The second load value Vis about 10 to 80 times as large as the first load value V, and is, for example, about 10 to 30 times as large as the first load value V. The relationship in magnitude between the first load value Vand the second load value Vcan change depending on a specific value of the first load value V.

In this preferred embodiment, as illustrated in, the electrode sheet fabrication deviceincludes a rotation mechanismand supporters. The rotation mechanismrotates the support roll. The rotation mechanismis connected to the support roll. In this preferred embodiment, the rotation mechanismrotates the support rollin the direction of arrow Rin. It should be noted that the rotation mechanismmay rotate the support rollin the direction opposite to the direction of arrow R. The rotation mechanismis not limited to a particular configuration, and is constituted by an electric motor and gears, for example. The rotation mechanismis connected to the controller(see).

The supporterssupport the support roll. The supporterssupport the both axial portionsof the support roll.

The controllerillustrated incontrols the roll pressing machineas described above. The configuration of the controlleris not particularly limited. The controlleris, for example, a microcomputer. A hardware architecture of the microcomputer is not particularly limited, and includes, for example, an I/F, a CPU, a ROM, a RAM, and a memory device. FIG.is a block diagram of the electrode sheet fabrication device. As illustrated in, the controlleris communicably connected to, for example, the conveyor, the moving mechanism, and the pressing mechanism(specifically, the cylinder driver), and the rotation mechanism. The controllercontrols the conveyor, the moving mechanism, the pressing mechanism, and the rotation mechanism.

The electrode sheet fabrication deviceaccording to this preferred embodiment has been described above. As described above, the pressing rollsare rubber rolls at least whose outer circumference surfaces are made of rubber. Thus, as illustrated in, when the pressing rollsare pressed against the electrode sheet, the outer circumference surfaces of the pressing rollsare easily deformed. In particular, portions of the outer circumference surfaces of the pressing rollspressed against the electrode sheetcan be deformed. The deformed portions of the pressing rollscan become flat along the shape of the electrode sheet. If the pressing rollsdo not rotate and are kept pressed against the electrode sheetfor a long time, the deformed portions of the pressing rollscan be permanently deformed. If the pressing rollsin such a partially deformed state (e.g., permanently deformed state) rotate and are pressed against the electrode sheetto extend the uncoated portionsof the electrode sheet, these portions cannot be uniformly extended in some cases. For example, portions of the uncoated portionspressed by the deformed portions of the pressing rollscan extend to a small degree, as compared to portions of the uncoated portionspressed by non-deformed portions of the pressing rolls. Consequently, it can be difficult to extend the uncoated portionsuniformly.

In addition, if the pressing rollsdo not rotate and are kept pressed against the electrode sheetfor a long time so that pressed portions of the pressing rollsare thereby permanently deformed, the uncoated portionsof the electrode sheetcan extend excessively accordingly. Consequently, the excessively extended uncoated portionsof the electrode sheetcan be broken.

Further, if the pressing rollsare pressed against the electrode sheetto sandwich the electrode sheettherebetween with the support rollrotated by the rotation mechanism, a difference in rotation speed between the support rolland the pressing rollscan hinder appropriate extension of the uncoated portions(e.g., can break the uncoated portions).

In view of this, in this preferred embodiment, to extend the uncoated portionsas uniformly as possible, a predetermined pretreatment is controlled by the controllerbefore the uncoated portionsof the electrode sheetis extended. In this preferred embodiment, as illustrated in, the controllerincludes a memory, a tension adjuster, a movement controller, a conveyance controller, a pressing controller, and an extension controller. Each unit of the controllermay be implemented by one or more processors or a circuit.

Next, the pretreatment performed before the uncoated portionsof the electrode sheetare pressed by the roll pressing machineand extended will be described with reference to the flowchart of. As illustrated in, this pretreatment starts when the support rollsupports the electrode sheetand the pressing rollsare at the first position P. At the start of the pretreatment, the pressing rollsare not in contact with the electrode sheetsupported by the support rolland are separated from the electrode sheetand located above the electrode sheet. At the start of the pretreatment, the conveyoris not driven, and the electrode sheetis not conveyed.

In the pretreatment, first, in step Sof, the tension adjustershown inadjusts a tension of the electrode sheet. In this step, the tension adjusteradjusts the tension of the electrode sheetsupported by the support roll. As illustrated in, the electrode sheetsupported by the support rollis bridged across the unwinding rolland the winding rollof the conveyor. Thus, the tension adjusteradjusts the tension of the electrode sheetbetween the unwinding rolland the winding roll. In this step, the tension adjusteradjusts the conveyor(e.g., rotation of the unwinding rollor the winding roll) such that the tension of the electrode sheetreaches a predetermined reference tension. The reference tension is a tension of the electrode sheetwhen the roll pressing machinepresses the uncoated portions. The reference tension is stored in the memoryinbeforehand. In adjusting the tension of the electrode sheetby the tension adjuster, the electrode sheetis not sandwiched between the support rolland the pressing rolls. At this time, the pressing rollsare located above the electrode sheetand separated from the electrode sheet.

Then, in step Sof, the movement controllershown inmoves the pressing rolls(both the pressing rollsL andR in this step) to the second position P(see). In step S, the tension of the electrode sheetsupported by the support rollis set at the reference tension, but the electrode sheetis not conveyed yet. Before step Sis performed, the pressing rollsare at the first position Pas illustrated in. Before the conveyorstarts conveyance of the electrode sheet, the movement controllermoves the pressing rollsfrom the first position Ptoward the second position P. In this step, as illustrated in, the movement controllercontrols the moving mechanismto move the pressing rollsdownward so that the pressing rollsthereby move to the second position P. In moving the pressing rollsto the second position P, the movement controllerturns the press cylindersoff, that is, does not drive the cylinder driving device. When the pressing rollsare moved to the second position P, the movement controllerturns the press cylindersoff. The movement controllermoves the pressing rollsto the second position Psuch that the pressing rollsare pressed against the electrode sheetwith the first load value V(see) at the second position P.

In this manner, when the pressing rollsmove to the second position Pby the movement controller, the pressing rollscontact the second surfaceU of the electrode sheetbut are mounted on the electrode sheetby self weight of the pressing rolls. At this time, the pressing rollsare in the state of being pressed against the electrode sheetwith the first load value Vby self weight.

Thereafter, in step Sof, the conveyance controllerillustrated inconveys the electrode sheetalong the support roll. Here, as illustrated in, in the state where the pressing rollsare at the second position Pand the press cylindersare off, the conveyance controllerstarts conveyance of the electrode sheetto the downstream side in the conveyance path. In this step, the conveyance controllerconveys the electrode sheetby controlling the conveyor(see), and rotates the support rollin the direction of arrow Rto thereby convey the electrode sheetby controlling the rotation mechanism. In this preferred embodiment, in step S, the pressing rollsare pressed against the electrode sheetby self weight. Thus, in conveying the electrode sheet, the pressing rollsrotate in the direction of arrow Rin synchronization with rotation of the support roll. The rotation speed of the support rollat this time is equal to the rotation speed of the pressing rolls.

In this preferred embodiment, when a predetermined standby time T(see) has elapsed since the pressing rollsmoved to the second position Pby the movement controller, the conveyance controllerconveys the electrode sheetalong the support roll. The standby time Tis stored in the memory(see) beforehand. The standby time Tis not limited to a particular value, and is, for example, 0.1 second to 10 seconds.

After the conveyance of the electrode sheethas started in the manner describe above, step Sofis performed next. In step S, as illustrated in, the pressing controllerinpresses the pressing rollsagainst the electrode sheet. In this step, the pressing controllerpresses the pressing rollsagainst the electrode sheetfrom the second position P. Specifically, the pressing controllerdrives the cylinder driving deviceto turn the press cylinderson from the off state. Accordingly, the pressing rollsmove downward so that the pressing rollsare thereby pressed against the electrode sheetwith the second load value V.

In this preferred embodiment, when a predetermined reference time T(see) has elapsed since conveyance of the electrode sheetby the conveyance controllerstarted, the pressing controllerperforms control such that the pressing rollsare pressed against the electrode sheetfrom the second position P. The reference time Tis stored in the memoryofbeforehand. The reference time Tis not limited to a particular value, and is, for example, three seconds or less, preferably one second or less. The reference time Tis, for example, 0.1 second. The reference time Tmay be set in accordance with the rotation speed of the pressing rolls. For example, the reference time Tmay be a time necessary for the pressing rollsto make one turn in conveying the electrode sheetby the conveyor.

The reference time Tmay be zero. In the case where the reference time Tis zero, when conveyance of the electrode sheetby the conveyance controlleris started, the pressing controllerpresses the pressing rollsagainst the electrode sheetfrom the second position P. In this manner, the timing of starting conveyance of the electrode sheetby the conveyance controllermay coincide with the timing of starting pressing the pressing rollsagainst the electrode sheetby the pressing controller.

The pretreatment is performed in the manner described above. After the pretreatment has been performed, the extension controllerincauses the roll pressing machineto press and extend the uncoated portionsof the electrode sheet. In this example, as illustrated in, the extension controllerturns the press cylinderson to press the pressing rollsagainst the electrode sheetwith the second load value V, and controls the conveyor(see) and the rotation mechanismto transfer the electrode sheetto the downstream side in the conveyance path(see). In this manner, the uncoated portionsof the electrode sheetare pressed with the second load value Vand extended while being sandwiched between the support rolland the pressing rolls.